Two charge sheets have been filed against 15 people in connection with the killings of Shiv Sena's Punjab-based leaders Satpal Sharma and Durga Prasad Gupta by operatives of terror group Khalistan Liberation Force (KLF), the NIA said today.

The charge sheets were filed in a special court in Mohali yesterday under various sections of the Indian Penal Code, the Unlawful Activities (Prevention) Act and the Arms Act, the National Investigation Agency said.

Sharma and his son Kumar, who were followers of Dera Sacha Sauda, were killed on February 25 last year at Naam Charcha Ghar in Jageda area in Ludhiana, while Gupta was shot dead on April 23, 2016 in Khanna, also in Ludhiana.

The NIA said during investigation it was found that killings of Sharma, his son and Gupta were part of a trans-national conspiracy hatched by the senior leadership of the KLF.

"Eight incidents of killings or attempted killings were executed as part of this conspiracy between January, 2016 and October, 2017 in Punjab," it said, adding a charge sheet was filed in this connection earlier this month.

"The objective of the conspiracy was to destabilise the law and order situation in Punjab and to revive the fledgling terrorism in the state," the agency said.

"The conspiracy had its foot-prints in several countries including Pakistan, the UK, Australia, France, Italy and the UAE," the NIA said.

"As part of the conspiracy, large amounts of funds were supplied through Italy, Australia and the UK to the perpetrators of the killings -- Hardeep Singh and Ramandeep Singh."

"These funds were used by them to purchase weapons for executing the killings and other logistics," it said.

"The conspiracy included recruitment and training of Hardeep Singh and Ramandeep Singh in Italy, Dubai and the UA," the agency said.

The NIA said while Singh is the permanent resident of Italy, Ramandeep Singh belongs to Ludhiana.

"Both these persons were trained by one Gursharanbir Singh, a UK national. Another UK national, Jagtar Singh Johal, who has been arrested in the case, was involved in the funding of the conspiracy," it said.

The NIA said day-to-day coordination of the conspiracy was done by Pakistan-based Harmeet Singh alias PhD.

The charge sheets were based on the evidences collected from oral, documentary, material and electronic sources, it said.